1. Technical Field
The present disclosure relates to earphones and, particularly, to a carbon nanotube based earphone.
2. Description of Related Art
Conventional earphone generally includes an earphone housing and an sound wave generator disposed in the earphone housing. The earphones can be categorized by shape into ear-cup (or on-ear) type earphones, earphones, ear-hanging earphones. The earphones can be disposed in the ears of a user. The ear-cup type earphones and ear-hanging earphones are disposed outside and attached to the ears of a user. The ear-cup type earphones have circular or ellipsoid ear-pads that completely surround the ears. The ear-hanging type earphones have ear-pads that sit on top of the ears. The earphones can also be categorized as wired earphones and wireless earphones.
The earphone housing generally is a plastic or resin shell structure defining a hollow space therein. The sound wave generator inside the earphone housing is used to transform electrical signals into sound pressures that can be heard by human ears. Sound wave generators can be categorized according to working principles: electro-dynamic sound wave generators, electromagnetic sound wave generators, electrostatic sound wave generators and piezoelectric sound wave generators. However, all known sound wave generators use mechanical vibrations to produce sound waves and rely on “electro-mechanical-acoustic” conversion. The electro-dynamic sound wave generators are most widely used. However, the structure of the electric-powered sound wave generator is constricted by configurations of magnetic fields and magnets which are often heavy in weight.
Carbon nanotubes (CNT) are a novel carbonaceous material and have received a great deal of interest since the early 1990s. Carbon nanotubes have interesting and potentially useful electrical and mechanical properties, and have been widely used in many different fields.
What is needed, therefore, is to provide an earphone having a simple lightweight structure.